Skip to main content

Full text of "Timber for structural purposes / by E.A. Sterling."

See other formats


949 



IS 






I 



No . 



K\ 








Jl 1 









I I 








it \m 









l/V //V7 At / v 



limber For Structural Purpose 



Ami 



Announcement 
'I he >ffe J 

Timhi Leg mate Place 
Kd licit 
At Timber Supply at Rea* m le »t 
Modern Structural Re rt len 
Pi Tooa eticc and D 






I 1 



Mill < true o D 

he tire i xard 
I ire Rt irdents 
Wood Preeerva 




igH 



\ i IO \L LIBBER 




v Rf as o r io 



(TENS! Of A R 



IIC 



• 


















9 • • 



♦ 



• 



• • 



' 



» * • • 






• 



** 









Timber For 
Structural Purposes 



by 



E. A. STERLING 



' £DUCAT/oVj 



TRADE E 

DEPAR1 



XTEN5ION 

UM ENT 



ECONOMY - STABILITY 
SERVICE 



Published by the 



National Lumber Manufacturers Association 

Trade Extension Department 

Chicago, Illinois 



January, 1916 



Engineering Bulletin No. 1 January. 1916 



ri 



\ 



Timber for Structural Purposes 

By E. A. Sterling 



Announcement The National Lumber Manufacturers As- 
sociation, through its Trade Extension De- 
partment, is preparing a series of engineering publications on 
structural timber. The word "timber," in this case, is inter- 
preted in its broadest application to all wood products used in 
construction. These bulletins will be available to all who are 
interested in standard and economical wood construction. The 
possibilities and advantages of lumber in modern structures, 

as well as its limitations, will be fully and frankly outlined, 
and reliable information as to strength, durability, and other 
characteristics, presented. Supplementing the information on 
the qualities of timber as a building material, details of proper 
design, working drawings, new developments, and similar data 
will be published. Modern wood construction in its many en- 
gineering phases will he presented on its own merits, with prej- 
udice towards no other building material. Many materials 
are embodied in the best designed structures, each with individ- 
ual merits and special fitness for the purpose. 

Service for Where wood products are better or as good, 

Architects, or by proper treatment can be made equal to 

Engineers and any other material, it is the legitimate desire 
Builders of the lumber industry that their selection 

and use shall be given full consideration. The 
policy will be to present engineering data relating to timber 
as a structural material, and in a spirit of helpful service to 
advocate the use of wood in construction wherever it fully 
meets all requirements of safety and economy. The informa- 
^ tion the manufacturers are ready to give should result in inu- 

CT tual benefit, since the thoughtful intelligent use of structural 

f? Page thrre 



TIMBER FOR 



timber will assure the erection of buildings embodying strength, 
symmetry, fire-resisting qualities and permanence to an extent 

which will reflect credit on both the material, the designers 
and the builders, and be looked upon favorably by insurance 
companies and the compilers of building ordinances. The 
service proposed goes farther than dissemination of informa- 
tion, because back of the whole movement is Association effort 
which aims to furnish structural timber which is standard as 
to size and quality, classified definitely by grading rules, and 
in the case of some of the more important species, trademarked 
as a guarantee of grade and quality. 



Engineering Timber is one of the most essential and widely 
Data used materials of construction. Modern engi- 

neering practice and the highest development 
of architectural skill find use for structural timber of many 

kinds in a wide variety of structures. \Vhil< many other 
excellent building materials have come into mm for purposes 
to which they are particularly adapted, timber retains the 

inherent advantage of economy, permanence, strength and 
safety. Knowledge of the material, coupled with its wise use . 
underlie the attainment of these service requirements with an\ 

building material. Since timber for many purposes is the most 
idap table and the must available of any material, it is impor- 
tant that its possibilities and advantages, as well as its limita- 
tions, m standard construction, should be mon generally 

k» 



IO\\ ii 



Frank recognition is given to the fact that engineering and 

scientific study has not bt « n as fully developed with structural 

timber as w ith some other materials, nor have the Available facts 

as to the strength and other physical ehararli risticfl of woods 
been given as wide appli< tion in construction work as the im- 
portance of the material justifi The comparath e absena of 
thes4 engineering data is. however, a condition of the past 
rather than tin pi tit. Tin United States J < st Products 
Laboratory, sonu of th< railroad testing departments, and a 



/'> _' "U 



STRl ( 'TV HAL PURPOSES 



number of educational institutions have been accumulating data 
for many years. While some of the invest iff at ions were not in 
accordance with the comprehensive plan which would lead to 
uniformly definite results, sufficient facts arc at hand to meet 
all practical requirements. 



Timber's The fundamentals in the proper and satisfac- 
Legitimate tory use of structural timber arc that the kind 
Place and grade should la- properly selected to meet 

specific service requirements; that the members 
should be incorporated in the structure in accordance with the 
best engineering and architectural knowledge of safe and p< i 
nianent design; and where not suitable for a particular use 
in its natural state, that the timber should be treated to prei en1 
deca) or retard fire and thus adapted to the requirements of th< 
structure. Anv building material mai fail or become a menaci 
to human life and property if improperly used. The lumber 
industiN knows that its material is safe and economical when 
properly used. It does not want lumber used under any other 

condit ion. 



Educational Structural timber and wood products generall) 
Publicity have not been extensively advertised, h cause of 

the assumption that their merits were already 
known. As a matter of fact, wood has been such a c immon 

n ml;i\ article that the universal familiarity with it has h d 

to a very general rather than specific knowledge of its quali 
ti< a and uses. More definite information is t<> be disseminated, 
not because the average engineer, builder or carpenter d< s not 
knew the general value of wood for construction purposes, hut 

for the reason that the last use and the safe si im come from 

more intimate knowledge of kinds and grades <»!' timber in r< hi 

tion to the place they are to be used. The strength char act* r- 
istics, resistance to decay, and possibilities of treatment t 
nlapt non-durable or cheaper grades to proper condition of 
sen are neglected subjects. Si no wood is a natural prod- 



>' - 



TIMBER FOR 



uct and is not manufactured in accordance with specifications 
and methods which give certain uniform results in the finished 
product, it follows that general knowledge of lumber should be 
supplemented by the results of technical investigations as to 
the character and quality of different woods, under varying 
conditions of growth and service. 

Available Good lumber is just as obtainable, possesses the 
Supply s ame structural characteristics, and is as safe and 

economical today as it ever was. In fact, with the 
development of transportation facilities and the better class- 
ification of kinds and grades, timber is more generally available 
and the quality better adapted to varying requirements than 
twenty years ago. Supplementing these advantages, are the 
recent data on physical characteristics, and the development 
of wood-preserving and fire- retarding materials and processes. 

Tlie Tnited States Government estimates conservatively 



place the amount of merchantable standing timber in the 
United States at over 2800 billion feet. This is slightly more 
than half of the original stand, the difference representing 
what lias been utilized for general consumption, what has been 
cleared from agricultural lands and what has been destroyed 

by forest fires and waste. Dining the past fifty years there 
has been a natural shifting in the sources of lumber production, 
with a less marked change in the centers of consumption. In- 
dustrial development has moved gradually westward and 

southward, following to an extent the opening up of new for* st 

regions as railroad facilities were extended. In some of the 
earlier regions of greatest lumber production the supply has 

lx i n greatly reduced, although local requirements are still sup- 
plied, except in huge dimension timbers which have to come 
from the more distant points. Hut nowhere, even in the tree- 
less regions, is there any difficulty in obtaining structural timber 

or wood products of kind and quality to meet all needs. 

Most of the present availabl- standing timber is in fi\ I gi'< at 

forest regions, namely, the Northern. Central. Southern, Rocky 



J } a <j ( 



STRUCTURAL PURPOSES 



Mountain and Pacific, with fully half the reserve supply in the 
Pacific Northwest. Rail transportation links each of these 
with the points of demand. Agricultural and industrial devel- 
opments have made the great central states and the middle tier 
eastward to the Atlantic the largest consuming centers. Water 
transportation now brings the enormous timber supply of the 
Pacific Coast closer to the larger centers of population in the 

East; while the cheaper water rates also result in a large move- 
ment of lumber from the Gulf ports and the south Atlantic 
states to the distributing cities in the Northeast. 

The present merchantable supply of timber will last nearly 
sixty years at the present rate of cutting. This, however, by no 
means indicates that the supply will be exhausted at the end of 
that period nor that exorbitant prices will ultimately prevail. 
The protection being given to forests against destruction by 
rire, the lower per capita consumption, the use of timber more 
wisely and by treatment or selection assuring longer life in 
service, the adoption of more intensive and less wasteful log- 
ging methods, the utilization of non-agricultural lands for for- 
est production, and the annual growth throughout the enor- 
mous forest area will, before a period of exhaustion is at hand, 
bring the nation's annual wood production up to an amount 
approximating the consumption, and secure an adequate sup- 
ply for an indefinite period. 

Messrs. W. B. Greeley and II. S. Betts, of the U. S. Forest 
Service, in a paper presented at the International Engineering 
Congress in San Francisco September, 1915, state as follows: 

"With its enormous areas of non-agricultural lands, appait ntly best 
suited to the production of timber, in the natural order of tilings, it is prob- 
able that the United States will not only supply its own needs but continue 
to be a large exporter of timber. Even the quality of the lumber placed 
upon the market, which is of primary interest to the structural engineer, 

will chance hut verv gradually as old sources of supply renew their stands 
of merchantable material. For the next thirty or forty years at least, there 
is no question as to the ability of the United States to furnish high-grade 
structural timbers from its southern pine and Douglas fir forests, to meet 
almost anv demand for such material from any portion of the world." 



Page seven 



TIMBER FOR 



As a further indication that lumber of all kinds is available 
for all purposes, the following estimate of annual production is 
quoted from "Lumber and Its Uses," by R. S. Kellogg: 



Lumber Production in the United States. 

Million 
Species Bd. Ft. Most Largely Produced in 

Yellow pine 16,000 ha.. Miss., Tex., X. C, Ala., Ark., Va., 

Douglas fir 6,000 Wash., Ore., Calif. 

Oak 4,400 W. Va., Tciin.. Ky.. Va., Ark., Ohio 

Northern pine 3,000 Minn.. Wi>.. Me.. N. H., Mich. 

Eastern hemlock 2.500 Wis., Mich., Pa.. W. Va. 

Western jrellovi pine 1.400 Calif ., Idaho, Wash., Ore. 

Maple 1.200 Mich., Wis., Pa., N. Y. 

Eastern spruce 1,100 Me., W. Va., N. H., Vt. 

< iypress 1,100 La.. Fla., Ga.. Ark. 

Yellow poplar 800 W. Va.. Tenn., Ky.. Va., X. C. 

lied gum . &00 Ark.. Miss., Tenn., La. 

Ch.-tnut G50 W. Va., Pa., Va., Conn., N. C. 

Redw ood 525 ( alifornia 

Beech 475 Midi.. Ind.. Pa., Ohio, X. Y., W. Va. 

Birch 425 Wis.. Midi.. Me.. Vt., X. Y. 

We rn white pine 400 Idaho. Wash., Mont. 

Basswood 3T5 Wis., Midi., W. Va., X. \ . 

( !< .1 ton wood 350 Miss., Ark., La.. Mo. 

Elm 325 Mich., Wis., Ohio, Ind., Mo. 

Western larch 300 Mont., Idaho, Wash. 

Western >pruce 300 Wash., Ore., Colo. 

Western hemlock 300 Wash., Ore., Idaho 

Hickory 300 Ark.. Tenn.. Kv.. Ohio, Inch 

Ash .' . 275 Ohio. Ark., Ind., Tenn., Wis. 

Western cedar 250 Wash., Idaho, Ore., Cal. 

White fir 140 Cal., Ore., Idaho 

Sugar pine 140 California 

Tupelo 140 La., X. C, Ala., Va. 

Tamarack 125 Minn.. Wis., Mich. 

Eastern cedar 125 Tenn., Va,, Mich., Ala. 

Balsam fir 100 Me., Minn., Vt., Mich. 

Sycamore 55 Mo., Ind., Ark., Tenn. 

Walnut 45 Ohio, Ind.. Kv., 111., Mo. 

Cherry 25 W. Va.. Pa., N. Y., Ohio 

Buckeye 25 Tenn., W. Va., X. C. Ky. 

Willow . . 20 Mississippi 

Noble fir 17 Oregon 

Magnolia 10 Louisiana 

Other species 38 

Total 44,550 

Page eight 



Fla., 



STRUCTURAL PURPOSES 



The annual average wood consumption, excluding firewood 
and rails', in the l r nited States for the past few years has been 
about V2 billion feet B. M. Of this amount some 40 biilion 
feet is in the form of manufactured lumber. The percentage 
of this total used for construction purposes has not been deter- 
mined accurately, the best figures indicating that about 20 per 
cent of the entire consumption is used for engineering con- 
sumption. While accurate figures are of no particular value, 
it is interesting to know that the timber used annually in en- 
gineering construction has an estimated valuation of fully 
$100,000,000. 

The per eapita consumption in the United States has 
always been higher than in most other countries — about .500 
hoard feet per capita in 190.5 — because of the liberal use of 
the most widely available building material. As wood is used 
more wisely, its life will increase, and as more timber is ere- 
osoted or given other preservative treatment, the annual renew- 
als for any class of structure will naturally decline. On the 
other hand, educational propaganda and the application of 
standard and permanent timber construction by the engineer- 
ing profession, will tend to increase or at least maintain the 
present lumber consumption for perhaps a decade. Follow- 
ing this, since renewals will be reduced by a more proper use 
of timber, there will be a falling off in consumption, the 
demand then being for new structures and for the reduced 
volume of renewals. To the structural engineer the possibil- 
ities in this line are very great . 



Quoting again from Messrs. Greeley and Betts: 

"The country is thus evidently drawing upon its forest capital at the 
rate of 60 to 70 billion feet annually (including the loss by tire and insects). 
Long before the present enormous forest resources are eaten up, however. 
it is more than probable that readjusting eeonomic conditions, particularly 
higher values for timber and a lower per capita consumption, will reduce 
the annual drain to an amount not more than the annual growth." 



Page nine 



TIMBER FOR 



Relative '^ le l yrict °* l umuer * las fluctuated in accordance 
Cost w ^h ti*adc and economic condition* in much the same 

degree as other materials. A comparison between 
certain species in an abnormal year, such as 1895, with a year 
of marked business activity as in 1905, might show a difference 
of as much as one hundred per cent. An analysis of prices 
shows, however, that averaging years of depression with periods 
of active demand, lumber follows as nearly a normal curve as 
most other materials. 

The following tabulation, compiled from the Report by the 
Census Bureau and Forest Service of the average price per 
thousand feet at the sawmills of the principal kinds of lumber 
from 1899 to 1912, shows clearly the course in lumber prices 
during this period. 



Average Mill Prices of Principal Kinds of Lumber. 



Kind of 
Wood 



i'.»l 



-» 



li'll l'.HO 



,.,,,.. 



190> 



iuo; 



1«J06 1904 



1899 



All kin. Is $1535 $15.05 $15.30 $15.38 $15.37 $16.56 $16.54 $12.76 $11.13 



"i ill<>\\ pine .... L4.3I 

Douglas fir 1 1.5* 

White pine 19.13 

Hemlock 13.68 

\\ «-i.r?i pine . . . 13.62 

Spruce 1 7.o:j 

Cypress 20.09 

Redwood 14. 13 

I edar 14.4:. 

Larch 1 1.96 

White fir 9.*6 

Tamarack (1) 

Sugar pin*' ..... 1 1 1 

Balsam tir x i) 

Lodgepole pine . . l > 

Dak 19.6 

Maple 15.56 

Yellow poplar. . . 24.06 

Red gum 12.60 

( hestnut 16.62 





SOFTWOODS. 










13.87 


13.29 


12.69 


12.66 


14.02 


15.02 


9.96 


8.46 


11.05 


13.09 


12.44 


11.97 


14.12 


14.2(1 


9.51 


8.67 


18.54 


18.93 


1*.16 


1*.17 


19.41 


18.32 


14.93 


12.69 


13.59 


13.85 


13.95 


13.65 


15.53 


15.31 


11.91 


9.98 


13.88 


l 1.26 


15.39 


15.03 


15.67 


14.ol 


11.30 


9.70 


16.14 


16.62 


L6.91 


16.25 


17.26 


17.33 


14.03 


1 1.27 


20.54 


20.:. l 


20.46 


21.30 


go i •> 


2 1 .94 


17.50 


13.32 


13.99 


1 5 . 5 2 


14.80 


15.66 


17.70 


H 4 


12.83 


10.12 


13.86 


1 5.5". 


19.95 


18.03 


19.14 


18.12 


14.35 


10.91 


11>7 


11.85 


12.39 


1 1.81 


13.07 


1 1 .9 1 


*.94 


8.00 


10.64 


11.5 2 


13.10 


11.38 


15.45 


12.91 


(1) 


<D 


( 1 1 


13.30 


13.18 


12.86 


15.71 


15.63 


12.42 


12.48 


i ; . 5 2 


18.68 


J*. 14 


17.78 


19.84 


16.11 


(1) 


12.30 


13.42 


14.4* 


13.99 


14.36 


16.16 


(1) 


(1) 


(1) 


12.41 


14.*- 


16.25 


H» 


Hi 


Hi 


ID 


(1) 




HARDWOODS. 










19.14 


18.76 


20.50 


21.23 


2 1.2: J 


21.76 


17.51 


13.78 


15.49 


16.16 


1 ■>., i 


L6.30 


16.84 


15.53 


14.94 


11.S3 


Z 5.4( ; 


24. ri 


25.39 


- - * * • » ' 1 


24.91 


2 4.21 


18.09 


14.03 


12.11 


12.26 


13.20 


13.08 


14. 10 


13.46 


10.87 


9.63 


16.63 


1 


16.12 


16.27 


17.04 


17.49 


1 '* 


13.37 



Page ten 



STRUCTURAL PURPOSES 



HARDWOODS — (Continued) 

Birch 17.43 1(3.61 17.37 16.95 16.42 17.37 17.24 

Beech 13.51 14.09 14.34 13.25 13.50 14.30 14.05 

Basswood 19.26 19.20 20.94 19.50 20.50 20.03 18.66 

Hickory 23.29 22.47 26.55 30.80 29.66 29.50 30.42 

Elm 16.87 17.13 18.67 17.52 18.40 18.45 18.0S 

Ash 20.27 21.21 22.47 24.44 25.51 25.01 24.35 

Cottonwood 20.44 18.12 17.7S 18.05 17.76 18.42 17.15 

Tupelo 13.61 12.46 12.14 11.87 13.36 14.48 14.13 

Sycamore (1) 13.16 11.10 14.77 14.67 14.58 (1) 

Walnut (1) 31.70 34.91 42.79 42.53 43.31 42.25 



15.44 


12.50 


(1) 


(1) 


16.86 


12.84 


:J3.94 


18.78 


14.45 


11.47 


18.77 


15.84 


14.92 


10.37 


(1) 


(1) 


(1) 


11.04 


45.04 


36.49 



(1) Not reported separately. 

The values are not intended to cover all grades of lumber 
nor to indicate market prices in all localities. They are how- 
ever, a correct basis for comparison of values at the sawmill, 
and show that there has been no undue advance in lumber 
prices, nor one out of proportion to the general rise in com- 
modity prices during the same period. 

The statement that lumber has reached such an exorbitant 
price that it can no longer be used, is best met by the records of 
the United States Bureau of Labor Statistics, the authority on 
the wholesale prices of all commodities. On page 266 of Bul- 
letin 181 of the Bureau is given a table of the relative prices 
of nine groups of commodities from 1860 to 1914, the average 
price from 1890 to 1899 being taken as 100. The chart on 
page 12 shows in graphic form the record of the Bureau for 
three of the most important groups of commodities; farm 
products, food, and lumber and building materials. On the 
chart, farm products are indicated by a dotted line, food by a 
line of dashes, and lumber and building materials by a solid 
line. A single glance at the chart completely answers the pop- 
ular statements as to undue advances in lumber prices. On an 
average, these prices have run between those of farm product^ 
and of food for the last fifty years, and with neither as high 
points nor as low points as the two other groups. Still further, 
it will be noted that the prices of lumber and building materials 
are relatively lower now than they were forty years ago: yet at 

« 



Vane eleven 



TIMBER FOB 



FARM PRODUCTS FOOD £7C- --LUMBER AND BU/LD/NC MATERIALS 




\ 



that time no one thought that lumber was too expensive to 

build with. The price of lumber at the end of 11)14 was lower 
than at any time since 1900, and even with the increase in prices 
which occurred the latter part of 1915, was on January 1, 1916, 
still less than in 1912. 



ern 



Mod 
Structural 



Modern structures impose Aery strict require- 
ments on the material used. It is for the struc- 

Requirements tural engineer rather than for the consumer 

to determine what material is best in particular 

locations. This selection is further determined bv city build- 

ing codes, by the need for safety from fire, and the necessity 

for permanence in congested city districts. 



Pane tivelve 



STRUCTURAL PURPOSES 



It is a logical development that structural timber should 
not be used in sky-scraper districts. The question of wooden 
floors, doors, inside trim, and fire-resistant construction is a 
problem for the engineer. There is ample evidence that the 
tendency in many cases has been to go too far in the elimination 
of wood, since its modern nse for these purposes is not the con- 
tributing cause of tire. At any rate, the character of the eon- 
tents is the underlying conflagration hazard in many cases, as 
evidenced by the burning out of the central districts of cities 
such as Baltimore and San Francisco. 

For factory and warehouse purposes, suburban and country 
dwellings, and in many other situations, wood may safely pre- 
dominate, and if properly used meets all requirements. With 
the basic facts of availability and economy established and data 
available as to strength and durability, the engineer can readily 
specify the extent to which structural timber may be safely used 
to the advantage of the owner or community. 



Permanence Permanence as applied to construction is a 

anc l relative term, since outside of definitely 

Depreciation planned and congested city districts perma- 

nence may mean a building lasting ten 



years or fifty years, according to the conditions. Both com- 
mercial buildings and dwellings serve their original purpose 
only while community or industrial conditions make their occu- 
pancy attractive or profitable. The growth of nearly all 



Ameri 



of residential streets 



to factory or warehouse districts, with no way of anticipating 
ultimate developments. The capitol at Washington, for in- 
stance does not face the main part of the city, because it did not 
grow in the direction which was anticipated. 

The lack of stability in city development does not mean 
that strictly temporary, unsafe, or unsightly structures should 
be built, but it does indicate definite advantages in the use of 
timber as the main structural material in dwellings and com- 



Page thirteen 






TIMBER FOR 



mercial buildings of moderate size and cost Many mill con- 
structed buildings in New England are practically as good 
today as when built a hundred years ago; while frame dwell- 
ings will last for generations, as evidenced by colonial homes 
which are still sound and comfortable after more than a cen- 
tury of use. The main point is that whether used for perma- 
nent or temporary purposes, timber structures may be removed 
or changed more readily, and may be adapted and remodeled 
more economically than if built of materials which in them- 
selves are claimed to be more permanent. 

The question of depreciation in buildings of all kinds is very 
important. So many factors must be considered that deprecia- 
tion on any type of building — wood or other material cannot 
be fixed on any absolute rule or percentage, nor in an arbitrary 
manner. Service records on wooden, brick and stone buildings 
run back through many years, and establish a basis for average 

depreciation figures. Some of the newer building materials, 

however, as well as some of the newer types or designs in struc- 
tures, have not been given this test of time. In buildings of 

the standard mill construction type depreciation is commonly 

estimated at from 1 to 1 ' . per cent annually. This, of course, 
is based upon well designed buildings, properly constructed of 

good materials. Comparative depreciation charges between 

different types of buildings will be more or less arbitrary, no 
mattei' how carefully compiled, because they depend not onl\ 

on the actual life of the building and on the character of th< 
occupancy, but on the indefinite period of usefulness, regard- 
less of the material. Taking into consideration several prin- 
cipal factors, such as community changes, expansion of city 

growth, developments in architectural types, and bousing re- 
quirements, a thirty to forty year period is a fair estimate of 

the term of usefulness of anv kind of structure. In view of 
this, well designed and properly built timber structures will in 

many cases meet all requirements of occupancy and use. and 

prove verv economical, both in first cost, and in ultimate altera- 
tions or removal. 



J'<i_< fourii 



STRUCTURAL PURPOSES 



Fire A stick of timber will burn and so will a wood, a 

Hazard . brick, a concrete, a steel or a terra cotta building. 

Buildings burn, not because of the materials of 

which they are built, but on account of faulty construction, 

lack of tire precautions, hazardous contents and carelessness. 

Tbe enormous annual fire losses in the United States very 
properly constitute a subject of national concern and every 
possible measure should be taken for their reduction. But that 
the general use of wood in the ordinary types of structure is 

the basic cause of tires is not a reasonable assumption. 

To condemn wood in any form and to advocate tin* use <>1 
noncombustible building material has been the aim of several 
publicity campaigns. The American people are too sane to b< 
led into a frenzv of condemnation against a material which has 



• 



sheltered and sen ed them from time immemorial, and a rtainly 

engineers and architects will continue l<> seled building mate- 
rial on its merits. The first consideration in the usi of timber 
is that it should never he placed in a structure where undent nt- 
ing experience has not shown it to be reasonably safe. On th 

other hand, its elimination because of the \\id -spread slogan 

thai "wood burns," and in favor of more expensive, less adapt- 
able and less beautiful materials which have no1 stood th serv- 
ice test of time, is as unreasonable as to drink wine instead of 

water because the latter may contain disease !M rms. There is 

_, statistics. 

One of the greatest fallacies is that of drawing conclusions 

regarding fire losses from per capita data. To say that the 



annual fire loss in the United States is $2.50 per capita against 
58-cent per capita loss in Europe is to ignon i necessarj meas- 
ure oi' value. The fact that the United States has about three 
and one-half times the number of tires and also \er\ nearly 
three times the number of buildings, leads to the simple con- 
clusion that Europe has fewer fires because it has fewer build- 
ings. Not onlv do we have nearly thr times th< number of 
buildinus but substantially twenty-five percent le>s population. 
These figures are gleaned from the Underwrite! report tor 



Poi *n 



TIMBER FOB 



the year 1913. It develops from this same source of informa- 
tion that the average loss per fire in the United States was $532, 
while the average in European cities was $8*2 greater or ^614. 
From this it is apparent that the average building in the United 
States is a fourteen per cent better fire risk than the average 
building in European cities. 

The whole fire question with respect to timber construction 
largely resolves itself into the fact that the public has been told 
about the fires in wooden buildings, while little or nothing has 
been said about what actually happens to buildings of so-called 

non-combustible material. Fire prevention propaganda, based 
on proper construction, adequate safeguards, elimination of 
hazardous contents and carelessness, and the use of automatic 
sprinklers, will be welcomed by the Lumbermen and go farther 

towards actual reduction of losses than an attempt to create 

prejudice against wood. 

A great many reports on fire prevention and the use of 

structural materials in building, state that a carefully designed 
timber structure is as safe against fire as any other type of 
structure if all floors are isolated, elevators and stairways en- 

* 

closed in fireproof shafts with all openings protected by self- 
closing doors, and proper sprinkler systems used throughout. 

A heavy timber which has been charred bv fire becomes of 
slow-burning nature due to the charred coating, in the same 

manner that a solid Jog burns slowly. Even when chaired. th< 
timber loses but Little of its original strength, and the building 

is not distorted nor weakened perceptibly. 

Mill Mill construction is a type of structure which 

Construction has been well known to enmn<< is for manv 

years. Its advantages as an economical and 
substantia] form of building for warehouses, factories, and 
many other uses are as strong today as ever, if properly d< 

signed with well-selected structural timber. Ileavv mill cmi- 

ft 

struct ion with a sprinkler system is a very acceptable fire risk, 

is evidence d bv its being pre! rred o\ er .ill other risks bv st rone 



Pol n 



STRUCTURAL PURPOSES 



mutual fire companies in New England. In this same territory 

it is stated in "Engineering of Shops and Factories" by II. G. 

Tyrrell, C, E., that there are more wood-framed mills than all 

others combined. 

A bulletin is under preparation which discusses the details 
of standard mill construction from the standpoint of the struc- 
tural engineer. 

Dwellings The frame dwelling is our commonest type. It is 

cheap, beautiful if properly designed, permanent 
if built of well-selected timber, and fully meets all of the re- 

* 

quirements of the home builder and real estate owner. Manx 

of the possibilities and advantages of the moderate priced 
frame home have been ignored or overlooked because no archi- 
tectural skill or training was utilized in the design or construc- 
tion. Model plans are available from many sources, and while 
they are of great assistance to the man who cannot afford to 
consult an architect, it would be economy in the long run if 
such buildings, especially of the more pretentious type, could 
be constructed under the supervision of competent architects. 

A point frequently overlooked in considering other than 
frame construction for the dwelling is the relative heat radia- 



j-> 



Hon in walls of various kinds. In tests made bv the German 

* 

Government of heat transmitted per square foot of wall sur- 
face per hour, it was found that the frame house, with 7/l<> 
inch clap-boards, building paper, sheathing, lath and plaster, 
had a heat loss factor of .2.*J of a H. T. I \ per degree as against 
.37 for plain brick walls one brick thick, and .36 for brick walls 
one brick thick plastered inside.* In stone walls a thickness 
of 20 inches is required with sand stone to reduce the heat fac- 
tor even to ..'3.5, while with a 12-inch stone wall the loss was 
.4,5. Concrete blocks are in about the same class as limestone 
in coldness and will have a heat loss factor of about 35 to 50 
per cent more than frame construction. 



lor further details reference i> made to ;i publication mi ln-;itin- and ventilating 
issued by the Buffalo Ford Company of Buffalo, X. V.: also t<> the book on "Heating 
and Ventilating BuiMinu-.'' by Carix-ntcr. 



Pane seventeen 



TIMBER FOR 



With the public at present somewhat influenced by the bug- 
aboo that "wood burns" many prospective builders attempt to 
use non-combustible materials. Here again amateur effort is 
not likely to bring gratifying results, and if the architect is 
called in the builder will have an opportunity to learn the 
actual relative merits and fire hazard of different types of 
dwellings. Even if the factors of beauty and economy can be 
taken care of in the home built of other than frame construc- 
tion there remains the fundamental cause of fire, which is in 
no wav influenced by the character of the structure. The elim- 

• * 

ination of individual carelessness is the first essential, after 
which the severity and frequency of the dwelling house fire is 
determined by the character of the contents. 

The frame dwelling has advantages of warmth, low cost, 
beauty and comfort which no other type can equal. All the 
sentiment of home centers around the "homey" character of the 
wood of which it is built. The treasures of the home will burn 
;:s quickly and completely within non-combustible vails as in 

a frame of wood. To banish the fire hazard, we should build 

tor safety by cutting off vertical openings, put smooth fire- 
clay Linings in chimneys, and if the home is not isolated from 
neighboring dwellings, use a fire-retardent preparation on the 

wooden shingles and a fire-resistant paint on the side walls. 

Then eliminate individual carelessness, take proper precautions 

always, and the home and all it means will be safe. 



pj re A developmenl which increases the adaptability 

Retardents °* UO(, d for many purposes, is along the line of 

fire retardents. Processes and materials have been 

perfected which are eminently practical. They are in most 

e;«M s a paint or chemical, which can be applied with a brush or 

by an immersion process. A special bulletin on tins subject is 
in preparation and for the present it is sufficient 1«» say that 
there are now <>n the market fire retardents which are esp< dally 
adapted to shingles, and will render them p< Eminently fin 

resistant in eater measure than many of the so-called iii< j - 



1' e hfrt 



STRUCTURAL PURPOSES 



proof roofings. Some of these same materials may be applied 
to other portions of the structure where it is desired to reduce 
the fire hazard. 

The same influences which have created a prejudice against 

the use of structural timber in commercial structures and franu 

dwellings have attempted to eliminate the ghingle roof. Tht 
propaganda is based entirely on I he fire hazard rince it is well 

known that good shingles, properly laid with good nails, will 

give better service than any other form of roofing material, 

and in case of fire in adjacent buildings can be met down so 

as to constitute an excellent lire break. No one denies that 
a dry shingle roof, particularly an old one, will ignite from 
brands and large sparks, nor does an\ sane man, lumberman 

or otherwise, advocate other than non-combustible roofs in con- 
gested city districts or wherever there is real danger. Hut it i> 

equally certain that many other roofing materials arc m the 

same class with shingles as regards inflammability, and when 
buildings are separated as in small towns and residential dis 

tries, the wooden shingle has qualities of beauty, economj 
storm resistance, and long life superior to any other roof 



covering. 



Wood With the advance in engineering knowledge 

Preservation there have come important developments in the 

preservative treatment of structural timber 
against decay. Treating processes have been applied on 

commercial seale in Europe for over a < ntury. and m 

this country for some forty years. The most extensive ao pt- 

ance of this practice has been by the railroads for treatment 
of cross-ties and structural timbers. bridg. trestles, dock 
etc. It is entirely feasible, however, to apply the same methods 
to the treatment* of structural timbers in many typ f build- 
ings, and the possibilities along this line have been lar. ly 
overlooked. St 1 is painted to prevent rust, eonerete is coated 
to prevent abrasion and to add waterproofing qualities, so it i 

Page nineteen 



TIMBER FOR STRUCTURAL PURPOSES 



entirely reasonable and in no way a reflection on the stability 
of timber that under certain conditions it should be treated with 
creosote, or some other preservative, to prevent decay. 

The inside timbers in many buildings where exposed to 
moisture should be treated with creosote. All timber in con- 
tact with the ground may be preserved indefinitely against de- 
cay. Mud sills and beams on foundations, basement planking, 
stringers, and other structural parts may be creosoted to secure 
permanence and stability. This not only reduces renewals to a 
minimum but establishes a constant factor of safety, since there 
is no reduction in strength from decay. Such timbers if given 
an empty cell treatment and left exposed to the air before 
being put in place will have no objectionable odor. In situa- 
tions where the color or use of creosote for any reason would be 
objectionable zinc-chloride may be used. 

The intelligent use of wood-preserving methods has the 
further advantage that the factor of durability in structural 
timber can be largely ignored and consideration given only to 
strength requirements. Many timbers which are naturally non- 
durable are cheaper than the more durable woods, thus effect- 
ing in the first cost a saving which largely covers the expense 
of treatment. 



Summary In this introductory publication an attempt has 

been made to review briefly the many engineering 
phases connected with the use of structural timber in mod- 
ern construction. The general announcement that the lumber 
manufacturers have under preparation a series of tech- 
nical bulletins dealing with timber and wood products in all 
forms, should be welcomed by all architects, engineers and 
builders. Their libraries have contained reference books on 
practically all building materials except wood, and this lack 
will now be supplied with the best engineering data on struc- 
tural timber and wood construction. These bulletins will be 
made readily available to all who are interested. 



Page twenty 
















'